Flow meters calculate flow rates, which is the volume of fluid that passes through a measurement point during a period of time. For example, utility companies may use flow meters to determine how much water a household used during a month to calculate monthly usage fees.
Measuring the flow rate of low volumes of fluids with low flow rates may be more difficult than measuring the flow rate of large volumes. Surface tension of the fluid and/or surfaces of the flow meter may affect the observed flow rate of the flow meter. For example, a plant may produce secretions on its stem. The stem may have a small observable area, and the secretions may occur over hours or days. Determining a secretion rate of the plant with traditional flow meters may not be feasible.